How is the xserver-support of omap?

Is it possible to play on the n900 an openGL game that is running on a big desktop (e.g. with a full featured ATI or Nvidia card)?

Can I transmit openGL by ssh -X?

No, this is not possible. The problem is that SSH never transfers frames, only controls and alike that are constructed on the system it runs on. So, if you run Gedit from Ubuntu to N900, Gedit will draw on N900's display, while Ubuntu wont handle processing the visuals. The same applies to GL. It will use the local X-server for rendering graphics, not the remote one. The conclusion is this: you cant play desktop games on N900 unless you use something similar to VNC. (VNC transfers graphics from an existing display, making it slower than SSH which transfers much smaller pieces.)

You are right:
ssh -X
transmits controls and not frames.

But this is exactly the reason why transmission of accelerated 3D graphics is POSSIBLE (e.g. aiglx).
openGL is NOT possible with VNC. Because VNC only transmits frames. But frames are useless for 3D Hardware acceleration.

openGL needs to have 3d objects (transmitted by controls, like postscript.)

ssh -X transmits 3D hardware controls with aiglx e.g.

My question is not if 3d graphics by ssh -X is possible.
I know that it is possible.

My question is if it is possible with the n900.

This depends on the implementation of SGX in the x-Server.
Is hardware acceleration supported in x-server?
Is it supported in a way that is compatible with transmission by ssh -X.
(e.g. GLX extension: texture_from_pixmap)